How to Make Dashi

Many cultures throughout the world have iconic, well-known dishes that utilize foundational ingredients integral to that region’s cuisine. For example, in Europe there is the powerful trio of vegetables known as mirepoix or sofrito that form the base of soups, stews, braises, and sauces. And the French prize the combination of butter and flour, for without it there would be no baguettes, croissants, or boeuf bourguignon. In the Mediterranean, olives and tomatoes thrive, and, therefore, form the backbone of many of the region’s dishes. 

Rice and soy sauce are undoubtedly foundational ingredients in Japan, but nothing quite captures the essence of Japanese cuisine like dashi. An island country dominated by mountainous regions, Japan has a close relationship with the sea and is well known for its love and appreciation of fresh fish. Though the two ingredients used to make dashi are both harvested from the sea, they are preserved and lightweight, making them easy to transport  all over the country. 


While preservation and transportation are important for starting food trends, dashi cemented its status in Japanese cuisine and history with its flavor, specifically its umami. The chemist who discovered umami in the early 20th century, Kikunae Ikeda, did so because he was trying to identify what made his wife’s dashi so satisfying. Dashi is high in umami thanks to its two main ingredients: kombu, an edible kelp that is high in glutamic acids, and katsuobushi, fermented fish flakes that are packed with inosinic acid. The impact of these two acids together is greater than the sum of their parts. Research has shown that while inosinic acid does not cause umami flavor on its own, it can exponentially amplify the presence of glutamic acid. 


Image Credit: Alice Wiegand, (Lyzzy) – Own work (CC BY-SA 3.0)

Kombu has been harvested and eaten by the Japanese for centuries. Large kelp forests grow in cold waters, and the northern island Hokkaido is where most of the kelp harvested for dashi is grown. Beginning in the Edo period, trade routes were developed that took the dried kombu from Hokkaido to Osaka, where it was then distributed to the mainland, and as far south as Okinawa. Mature plants that are ready to be harvested can be 30 ft long. Once harvested, the kombu is stretched out to air dry in the sun, with the harvesting season running from early to late summer. 


Image Credit: Sakurai Midori – Own work (CC BY-SA 3.0)

Dashi gets its smoky flavor from katsuobushi. Filets of skipjack tuna or bonito (a smaller species in the tuna family) are dried, smoked, and fermented to remove all of their moisture. The hard planks are then shaved with a special box that has a thin metal blade mounted on it, similar to a wood planer. These shavings, sometimes called bonito flakes, are soaked along with the kombu to make dashi. Katsuobushi is also used as a garnish for some of Osaka’s famous dishes. The thin shavings are known to “dance” when they’re sprinkled on hot okonomiyaki or takoyaki due to the rising steam. 


Image Credit: Bluebird Provisions from Pixabay

There are a few common variations of dashi. Dried shiitake mushrooms are a frequent addition, as they help boost the rich umami flavor to even greater heights (they are high in guanylic acid, which acts similarly to inosinic acid to amplify umami flavor). Dashi can also be made vegetarian by substituting the katsuobushi for shiitake mushrooms. Niboshi, which are small anchovies, are also a popular addition to dashi.

Instant Dashi

Image Credit: Flickr user bike (CC BY-SA 2.0)

While dashi requires few ingredients and is simple to prepare on its own, many people prefer ready-to-use packets or instant dashi granules. One of the most widely available brands (including in U.S. supermarkets) is from Ajinomoto Hondashi. Instant dashi granules are also a great way to add the flavor and umami to dishes without needing to add extra liquid. 

Dashi Recipe

Unlike broths or stocks that require hours of simmering or boiling to extract flavor from meats and vegetables, dashi should never be boiled. Boiling brings out bitter, astringent flavors from the kombu. Instead, it’s better to think of dashi like a tea or coffee that needs to be steeped to extract its delicate and balanced flavor. This recipe is inspired by the one found in Ivan Orkin’s The Gaijin Cookbook.


Makes 4 cups

  • 1 large pieces of kombu, 3 x 6 inches
  • 2 cups shaved katsuobushi (bonito flakes)
  • 4 cups water

Bring 4 cups of water to a boil. Remove from heat, add the kombu, cover, and let steep for 20 minutes. Then add the katsuobushi and steep for another 10-15 minutes. Remove the kombu and strain out the katsuobushi. Dashi will keep for 3-4 days in the refrigerator or up to one month in the freezer.

Feature Image: Flickr user johnjoh (CC BY-SA 2.0)

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